1. Field of the Invention
The present invention relates to the field of proofing, more particularly to the field of proofing with digital imaging, especially thermal transfer media and ink jet media, and most particularly to the field of visually calibrating proofs made by digital generation of colors.
2. Background of the Art
Prepress proofing of printed images is intended to provide a printer with a simulation or estimate of an image which is to be printed. This simulation is prepared off the press, rather than going through the expensive and timely procedure of dedicating the press to an actual run to qualitatively evaluate the accuracy of printing plate exposures.
Proofing operates by using a set of color separations (physical or electronic) which will ultimately be used to expose a printing plate to generate a printed image. The same set of color separations is used to generate the proof. At present, there are certain media which are specifically designed to simulate the image which would be produced on press by the data used in generating the proof. Even features uniquely characteristic of on press proofing can be built into the proof (e.g., dot gain, etc.).
It is most common for the proof image to be directly compared with the original image or the original individual color separations to compare results. The trained eye of the printer will suggest different levels of exposure to more properly reflect actual tones, hues and densities of the original image. In certain types of proofing, particularly digital proofing when accessing electronic data, there can be both variations in the proofing materials (lot to lot variations, for example), and there may not be an original image (other than the electronic data) to work from. This can complicate the job of the printer in determining how much alteration of the imaging process must be effected to perfect the proof image.